Commit | Line | Data |
---|---|---|
430400b8 UF |
1 | Kernel driver sht21 |
2 | =================== | |
3 | ||
4 | Supported chips: | |
5 | * Sensirion SHT21 | |
6 | Prefix: 'sht21' | |
7 | Addresses scanned: none | |
8 | Datasheet: Publicly available at the Sensirion website | |
9 | http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf | |
10 | ||
11 | * Sensirion SHT25 | |
12 | Prefix: 'sht21' | |
13 | Addresses scanned: none | |
14 | Datasheet: Publicly available at the Sensirion website | |
15 | http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT25.pdf | |
16 | ||
17 | Author: | |
18 | Urs Fleisch <urs.fleisch@sensirion.com> | |
19 | ||
20 | Description | |
21 | ----------- | |
22 | ||
23 | The SHT21 and SHT25 are humidity and temperature sensors in a DFN package of | |
24 | only 3 x 3 mm footprint and 1.1 mm height. The difference between the two | |
25 | devices is the higher level of precision of the SHT25 (1.8% relative humidity, | |
26 | 0.2 degree Celsius) compared with the SHT21 (2.0% relative humidity, | |
27 | 0.3 degree Celsius). | |
28 | ||
29 | The devices communicate with the I2C protocol. All sensors are set to the same | |
30 | I2C address 0x40, so an entry with I2C_BOARD_INFO("sht21", 0x40) can be used | |
31 | in the board setup code. | |
32 | ||
33 | sysfs-Interface | |
34 | --------------- | |
35 | ||
36 | temp1_input - temperature input | |
37 | humidity1_input - humidity input | |
38 | ||
39 | Notes | |
40 | ----- | |
41 | ||
42 | The driver uses the default resolution settings of 12 bit for humidity and 14 | |
43 | bit for temperature, which results in typical measurement times of 22 ms for | |
44 | humidity and 66 ms for temperature. To keep self heating below 0.1 degree | |
45 | Celsius, the device should not be active for more than 10% of the time, | |
46 | e.g. maximum two measurements per second at the given resolution. | |
47 | ||
48 | Different resolutions, the on-chip heater, using the CRC checksum and reading | |
49 | the serial number are not supported yet. |